We read in John 1:14 that Jesus is the only "begotten" or "one and only" son...
Begotten as used of Jesus is always the Greek word "Monogenes" which means only one to ever come from the Father. .. the sole representative of the Being and Character of the One who sent Him. In the original, the definite article is omitten before "only Begotten" and Father, and it's absence lays stress upon the chacteristics mentioned.
In using Monogenes, John is not merely making a comparison with the earthly meaning of the word.. and this is indicated by using the word "para" or from.
The glory mentioned is that of a unique relationship and not the beginning of His Sonship. It suggests relationship indeed, but must be distinguished from generation as applied to man.
Monogenes, denotes a fact that is irrespective of time. the Christ didn't become but eternally is, The Son. He possesses every attribute of pure Godhead.
John 1:18, describes Him in the eternal union with the Father.. Monogenes Theos.. God only-begotten.
Now.. when we look at begat or begotten .. another word is used
Gennao.. which means to be born, and is chiefly used of men begetting children. ..
It is the very word used to describe our position as being conferred with the nature of God, by being his children.
Other words used in the Greek, are Anagennao, Apokueol and Tikto, .. but none of thse are the words used of Jesus in His relationship with God.